Fuel cleanliness determination



Patented July 7, 1953 UNITED STATES 2,644,330 FUEL GLEANLINESS DETERMINATION Fredrick L. Jonach, Richmond Hill, N. Y., and James A. Wilson, Linden, and John J. Heigl, Cranford, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application March 1, 1951, Serial No. 213,457

. 1 This invention concerns a process for the determination ofwhat may be called the cleanliness properties of a fuel. In accordance with this invention, in. order to characterize a fuel as regards deposit formation during combustion, a sample of the fuel is burned under controlled conditions. The burning flame is directed onto a cooled surface to secure the condensation of water and other combustion products and in particular to secure the deposition of solid combustion products. These combustion products are then treated with an organic'gum solvent such as acetone. The quantity of the deposit dissolved in the acetone is then determined and in addition the quantity of the deposit which does not dissolve in the acetone is determined. By reference to correlated data, from the amount of acetone soluble deposit alone, or by reference to both the acetone soluble and insoluble deposit of the fuel, it is possible to characterize the fuel as regards engine cleanliness properties.

In recent years it has become increasingly apparent that an important criterion of fuels such as gasolines, jet fuels, kerosene and diesel fuels, is the amount of deposit. formed in an engine as a result of the combustion of these fuels. In part, due to the advent of fuels which contain large portions of cracked constituents, it has been found that relatively large quantities of engine deposits may be formed. The formation of these deposits in an engine is undesirable for a number of reasons. In the. case of automotive and aviation engines employing gasoline as the fuel, the formation of engine deposits increases the ring sticking tendency of the engine pistons, increases engine wear, etc. Again in the case of. jet engines, the operating life of a jet combustor is limited by the amount of combustion products deposited in the jet engine. Consequently, it is presently appreciated that the deposit forming properties of a fuel or in other words the cleanliness characteristics of a fuel are of real importance.

In order to determine means for improving the cleanliness properties of fuels, in order to control processes affecting the engine cleanliness, and in order to characterize and evaluate fuels,

it is essential to develop a simple and effective 5 Claims. (01. 73-53) test permitting accurate identification of the 7 cleanliness properties of a given fuel. This is essential since the quantities of fuel required, the time necessitated, and the expenses incident to full scale engine teststo evaluate fuels for clean- I I liness are prohibitive. Attempts have been made to develop chemical tests to indicate the cleanliness of fuels. While some. tests of this nature have been developed which are reasonably satisfactory'for particular types of fuels, no prior art tests have been found applicable to bothgasolines and jet fuels, for example. This fol-' lows from the fact that any chemical test is necessarily specific to one. compound or group of compounds of similar structure. Insofar as it has been determined that different compounds in different fuels affect the cleanliness properties of the fuels, it appears unlikely that it will be. possible to develop a suitable chemical test. Consequently, the present invention is directed to overcoming this limitation of chemical tests by developing a fuel characterization procedure based on the actual combustion of the fuel being evaluated.

In accordance with this invention, it has been discoveredthat the deposits resulting from combustion of 'a fuel may be processed by treatment with a suitable organic solvent so that the solubility characteristics of the deposit may be em ployed to predict the cleanliness properties of the fuel. Carefully controlled conditions of combustion are required in the practice of' this process. It has been found necessary toemploy an effective atomization of the fuel and to obtain essentially complete combustion of the fuel. In securing burning of this character under readily controlled conditions, it has been found effective to employ a conventional blow torch as the burning system, employing a burning rate of about to 120, preferably to 90, grams per hour. A given quantity of fuel, for example, about 1,000 cc. is employed in the test. The flame of the blow torch is adjusted to essentially complete combustion, and the products of. combustion are brought into proximity with a relatively cool surface which acts as a collector for-the deposits. For example, the flame may be directedinto the center of a condenser having a glass or metal cylindrical liner whose end. is immediately adjacent the burner tip. Av suitable cylindrical liner is about 3 inches in diameter and about 12 inches long, being jacketed to permit the circulation of cooling Water about the inner liner. It is important that the liner be sloped downwardly from the burner so that water and other liquid combustion products will collect out of the flame area. The products can be collected in the liner if a closed end liner is employed, or in a separate vessel if an open end liner is employed. It is important that a constant cooling effect be pro- .vided so as to maintain the liner at a closely conwater formed by combustion. When the liner has been dried in this manner and then cooled, it is filled with a suitable solvent such as CP acetone which has been distilled. Purification of the acetone by distillation is important as even the grade contains excessive amounts of gum. To facilitate solution of the liner deposit in the acetone, the liner may be scraped with a glass scraper and an abrasive such as a small piece of glass wool.

Finally, the total contents of the liner including the acetone, the deposits dissolved in the acetone, and solid deposits not dissolved in the acetone, are transferred to a filter. After filtration the acetone containing dissolved deposits is charged to distillation equipment. A small flow of a gas such as nitrogen is bubbled through the still to aid in flashing off the acetone. After distillation of 90% or more of the acetone, the remaining solution is then transferred to a beaker for evaporation to dryness on a steam bath. So called anti-creeping beakers are preferred for the final evaporation. After the beaker reaches dryness it is preferably dried in a vacuum oven, for example, for about one-half hour at 180 F., and 150 mm. mercury pressure. The weight of deposits remaining in the beaker are then determined. In addition, the weight of the solid deposits filtered from the acetone solution is also determined. 7

In a great number of tests which have been conducted, it has been found that this simple procedure is effective and accurate in characterizing the cleanliness properties of fuels. To demonstrate this the data in Table I may be referred to. In the data set forth, the weight of acetone soluble deposits for each fuel is given as determined according to the described pro cedure. In addition, the actual engine deposits obtained'in a full scale engine test are tabulated for each fuel. The test employed was the wellknown CRC-FL-2 engine test. As indicated in the table, the fuels employed were automotive aviation gasolines and blends with particular fuel constituents.

In order to establish the correlation between the acetone soluble deposits and the actual engine deposits, the acetone soluble deposits were plotted on a graph against the actual engine deposits for each of the different fuels. It was found that a substantially linear correlation exists between the acetone soluble deposits and the actual engine deposits. As a result, by referring to this graph, the actual engine deposits for any fuel tested may be predicted by determining. the graphical intersection of the correlation line referred to and the acetone soluble deposits determined. For example, in the case of fuel No. 8 of Table I, finding that this fuel provided 20.3 mgs. of acetone soluble deposits and referring to the graphical correlation between acetone soluble deposits and actual engine deposits, it was found that the predicted engine deposits would be 105. This value is given in Table I and the value determined by this procedure is also given for the other fuels under the column headed DEM. It is apparent that conversion of the acetone soluble deposits to the actual engine deposits is not essential since with experience, the acetone soluble deposits may be employed directly as a' measure of the engine cleanliness characteristics of any fuel.

TABLE I Deposit prediction method for the engine cleanliness characteristics of motor fuels FL-2 Percent 3 3 of Reference Fuel Description Deposits (Mgs') DPM Engine 1. Aviation Gasoline mm... 1.5 52 52 2. 40% cracked Naphtha and Aviation Gasoline 9. 8 77 3. Automotive Fuel u 13.2 83 77 4. 20% Reformed Naphtha and Aviation Gasolinemnnfl 16.0 92 95 5. 40% Light cracked Naphtha and 60% Aviation Gasoline... 17. 8 93 105 6. Referee Fuel .i 18.7 100 7. 50% Heavy Naphtha, 50% Av ation Gasoline 10.8 103 129 8. 20% Heavy Naphtha. 80% Aviation Gasoline 20. 3 105 108 9. Cracked Naphth 22. 9 111 93 10. Automotive Gasoli e 23.0 111 94 ll. 30% Cracked Napht 70% Aviation Gasoline" 27.0 123 124 12. 20% Heavy Naphtna, 80% Aviation Gasoline 3 27 123 l34 1S. Low-Press ate 29.8 1 131 14. 30% Cracket the, 70% Aviation Gasoline 31.3 133 I05 15. 20% Untreated Cracked Naphtha,

80% Aviation Gasoline 35. 8 147 148 10. 90% Cracked Naphtua, 10% Heavy Naphtha 63. 7 253 Average Deviation from FL-Z Engine Test :l;6%. Average of two runs. 2 Average of five runs. 3 Average of eight runs. 4 Compared to Referee fuel given a rating of 100.

The application of the characterization procedure of this invention is not limited to gasoiines. Thus, it has been found that jet fuels may also be evaluated in the test. To demonstrate this the data of Table II is presented showing the actual deposit obtained on combustion of five different jet fuels in a J-42 jet combustor showing the weight of deposit obtained by the procedure of this invention. The deposit obtained is reported as total deposit, acetone soluble deposit, acetone insoluble deposit, and corrected deposit.

1 Acetone soluble portion +33% of acetone insoluble portion. Grams formed in F42 Single Combustor.

From the data of the nature indicated in Table II, it has been found that the best correlations for jet fuels are obtained; that is, the best predictions of fuel cleanliness may be made, by determining both the acetone solubleportion of the deposit and the acetoneinsoluble portion of the deposit. A cleanliness rating may then be determined adding the acetone soluble deposit and a certain percentage of the acetone insoluble deposit. Again the predicted deposit may be established from a graphical correlation of the corrected deposits and the actual deposits in the same manner as described in connection with Table I. Such a correlation for each of the fuels'of Table II is given in Table II under the heading Predicted Deposit. The need for the acetone insoluble factorresults from the fact that in an actual jet combustor gas velocities are higher than those maintained in the deposit prediction method, and these high gas velocities cause some of the deposits to be blown off the For the particular liner of the jet combustor. jet combustor employed in the tests shown in Table II an acetone insoluble factor of 33% gives a good correlation, while for other combustors the factor may be higher or lower.

While the invention has been described with regard to the use of acetone as the solvent employed to treat the liner deposit, it is apparent that other solvents may be utilized. Ingeneral, it is preferred to employ relatively low-boiling solvents which can be easily removed by volatilization. Among the suitable gum solvents may be mentioned other ketones besides acetone such as methyl ethyl ketone and methyl isopropyl ketone, halogenated solvents such as chloroform, esters such as amyl acetate, ethyl acetate, etc., certain ethers such as dioxane, aromatics such as benzene and toluene, mixed solvents such as benzene and ethanol, etc. These specific solvents and other solvents which may be employed are characterized by Kauri-Butanol solvent powers of at least 100 by the test method designated ASTM D-1133.

While the test has been described with particular reference to the use of a blow torch as the burning system, any desired burner may be used provided carefully controlled burning conditions may be maintained to provide a flame which may be directed unto the condensing surface required. The fuels to which this technique may be employed are liquid hydrocarbon fuels consisting of gasolines, jet fuels, kerosenes, diesel fuels and heating oils. In the case of heavier fuels such as heating oils, it is generally necessary to reduce the viscosity of the fuels with gasoline, for example, to secure a fuel which may be burned in the burning equipment used for the test.

What is claimed is:

1. The process for characterizing a liquid hydrocarbon fuel comprising the steps of burning the fuel to be characterized in a burner system under constant conditions of combustion to provide an open flame, directing said open flame onto a cooled surface, whereby combustion products are condensed and deposited on said cooled surface, and thereafter dissolving deposits from said surface in an organic gum solvent having a Kauri-Butanol solvent power of at least 100, and determining the quantity of deposits dissolved in the said solvent.

2. The process for characterizing a hydrocarbon fuel comprising the steps of burning the fuel to be charatcerized in a burner system under constant conditions of combustion to provide an open flame, directing said open flame into a cylindrical cooled container, whereby combustion products are condensed and deposited in said cooled container, and thereafter dissolving deposits in said container in an organic gum solvent having a Kauri-Butanol solvent power of at least 100, and determining the weight of deposits dissolved in the solvent and determining the quantity of deposits insoluble in the said solvent.

3. The process for characterizing a hydrocarbon fuel comprising the steps of atomizing the fuel, burning the fuel to be characterized in a burner system with an excess of oxygen under constant conditions of combustion to provide an open flame, directing said open flame into a cylindrical cooled container, whereby combustion products are condensed and deposited in said cooled container, and thereafter dissolving deposits in said container in an organic solvent having a Kauri-Butanol solvent power of at least and determining the weight of deposits dissolved in the solvent.

4. The process of claim 3 in which the said solvent is acetone.

5. The process of characterizing a fuel comprising burning said fuel under controlled combustion conditions providing a burning rate of about 60 to grams per hour, directing the flame provided by this burning along a cooled condensing surface whereby combustion products are deposited on said surface, and thereafter drying said surface and dissolving said deposits to the extent possible in an organic solvent, and determining the quantity of deposit dissolved based on the quantity of fuel burned.

FREDRICK L. J ONACI-I. JAMES A. WILSON. JOHN J. HEIGL.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Ogilvy Aug. 18, 1925 OTHER REFERENCES Number 

2. THE PROCESS FOR CHARACTERIZING A HYDROCARBON FUEL COMPRISING THE STEPS OF BURNING THE FUEL TO BE CHARACTERIZED IN A BURNER SYSTEM UNDER CONSTANT CONDITIONS OF COMBUSTION TO PROVIDE AN OPEN FLAME, DIRECTING SAID OPEN FLAME INTO A CYLINDRICAL COOLED CONTAINER, WHEREBY COMBUSTION PRODUCTS ARE CONDENSED AND DEPOSITTED IN SAID COOLED CONTAINER, AND THEREAFTER DISSOLVING DEPOSITS IN SAID CONTAINER IN AN ORGANIC GUM SOLVENT HAVING A KAURI-BUTANOL SOLVENT POWER OF AT LEAST 100, AND DETERMINING THE WEIGHT OF DEPOSITS DISSOLVED IN THE SOLVENT AND DETERMINING THE QUANTITIY OF DEPOSITS INSOLUBLE IN THE SAID SOLVENT. 